Pick's disease immunohistochemistry: new alterations and Alzheimer's disease comparisons

Heparan Sulfate Proteoglycans in Tauopathy

Tauopathies are a class of neurodegenerative diseases, including Alzheimer's disease, and are characterized by intraneuronal tau inclusion in the brain and the patient's cognitive decline with obscure pathogenesis. Heparan sulfate proteoglycans, a major type of extracellular matrix, have been believed to involve in tauopathies. The heparan sulfate proteoglycans co-deposit with tau in Alzheimer's patient brain, directly bind to tau and modulate tau secretion, internalization, and aggregation. This review summarizes the current understanding of the functions and the modulated molecular pathways of heparan sulfate proteoglycans in tauopathies, as well as the implication of dysregulated heparan sulfate proteoglycan expression in tau pathology and the potential of targeting heparan sulfate proteoglycan-tau interaction as a novel therapeutic option.

GM3 Ganglioside Linked to Neurofibrillary Pathology in a Transgenic Rat Model for Tauopathy

Glycosphingolipids (GSLs) are amphipathic lipids composed of a sphingoid base and a fatty acyl attached to a saccharide moiety. GSLs play an important role in signal transduction, directing proteins within the membrane, cell recognition, and modulation of cell adhesion. Gangliosides and sulfatides belong to a group of acidic GSLs, and numerous studies report their involvement in neurodevelopment, aging, and neurodegeneration. In this study, we used an approach based on hydrophilic interaction liquid chromatography (HILIC) coupled to high-resolution tandem mass spectrometry (HRMS/MS) to characterize the glycosphingolipid profile in rat brain tissue. Then, we screened characterized lipids aiming to identify changes in glycosphingolipid profiles in the normal aging process and tau pathology. Thorough screening of acidic glycosphingolipids in rat brain tissue revealed 117 ganglioside and 36 sulfatide species. Moreover, we found two ganglioside subclasses that were not previously characterized-GT1b-Ac2 and GQ1b-Ac2. The semi-targeted screening revealed significant changes in the levels of sulfatides and GM1a gangliosides during the aging process. In the transgenic SHR24 rat model for tauopathies, we found elevated levels of GM3 gangliosides which may indicate a higher rate of apoptotic processes.

Complement C6 deficiency exacerbates pathophysiology after spinal cord injury

Historically, the membrane attack complex, composed of complement components C5b-9, has been connected to lytic cell death and implicated in secondary injury after a CNS insult. However, studies to date have utilized either non-littermate control rat models, or mouse models that lack significant C5b-9 activity. To investigate what role C5b-9 plays in spinal cord injury and recovery, we generated littermate PVG C6 wildtype and deficient rats and tested functional and histological recovery after moderate contusion injury using the Infinite Horizon Impactor. We compare the effect of C6 deficiency on recovery of locomotor function and histological injury parameters in PVG rats under two conditions: (1) animals maintained as separate C6 WT and C6-D homozygous colonies; and (2) establishment of a heterozygous colony to generate C6 WT and C6-D littermate controls. The results suggest that maintenance of separate homozygous colonies is inadequate for testing the effect of C6 deficiency on locomotor and histological recovery after SCI, and highlight the importance of using littermate controls in studies involving genetic manipulation of the complement cascade.

Primary progressive aphasias and their contribution to the contemporary knowledge about the brain-language relationship

Primary progressive aphasia (PPA), typically resulting from a neurodegenerative disease such as frontotemporal dementia/Pick Complex or Alzheimer's disease, is a heterogeneous clinical condition characterized by a progressive loss of specific language functions with initial sparing of other cognitive domains. Based on the constellation of symptoms, PPA has been classified into a nonfluent, semantic, or logopenic variant. This review of the literature aims to characterize the speech and language impairment, cognition, neuroimaging, pathology, genetics, and epidemiology associated with each of these variants. Some therapeutic recommendations, theoretical implications, and directions for future research have been also provided.

Argyrophilic thorny astrocyte clusters in association with Alzheimer's disease pathology in possible primary progressive aphasia

Although most cases of primary progressive aphasia (PPA) have one of the varieties of frontotemporal lobar degeneration (FTLD) as their pathological substrate, a subset shows Alzheimer's disease (AD) pathology. We report that all eight cases in our clinic diagnosed as possible PPA, on account of the presence of episodic memory difficulties in addition to severe language impairment at the onset of disease, showed AD pathology. Neither focal accentuation of AD pathology nor vascular lesions in language-related areas was observed. Seven of these eight patients showed large argyrophilic thorny astrocyte clusters (ATAC) in the fronto-temporo-parietal cortex and subcortical white matter. The intensely tau immunoreactive astrocytes in ATAC were morphologically similar to the perivascular, subpial, and subependymal astrocytes in elderly brains, but ATAC differ from the latter by the cortical and subcortical location, widespread distribution outside the medial temporal lobe, and intense argyrophilia. The location of ATAC was related to neither local variations in the load of AD pathology, nor the myelin density of white matter. ATAC were not seen in a comparison group of six cases of AD without a prominent aphasia syndrome. Because of the similarity of astrocytes in ATAC to those seen independently of AD pathology in several subtypes of FTLD and two reported cases of PPA we hypothesize that they are a marker of a pathological process concurrent with AD, and related to the focality of the clinical presentation.

Pick's disease: a modern approach

Pick's disease is a rare dementing disorder that is sometimes familial. The cardinal features are circumscribed cortical atrophy most often affecting the frontal and temporal poles and argyrophilic, round intraneuronal inclusions (Pick bodies). Clinical manifestations reflect the distribution of cortical degeneration, and personality deterioration and memory deficits are often more severe than visuospatial and apraxic disorders that are common in Alzheimer's disease, but clinical overlap with other non-Alzheimer degenerative disorders is increasingly recognized. Neuronal loss and degeneration are usually maximal in the limbic system, including hippocampus, entorhinal cortex and amygdala. Numerous Pick bodies are often present in the dentate fascia of the hippocampus. Less specific features include leukoencephalopathy and ballooned cortical neurons (Pick cells). Glial reaction is often pronounced in affected cerebral gray and white matter. Tau-immunoreactive glial inclusions are a recently recognized finding in Pick's disease, and neuritic changes have also recently been described. Variable involvement of the deep gray matter and the brainstem is typical, with a predilection for the monoaminergic nuclei and nuclei of the pontine base. Neurochemical studies demonstrate deficits in intrinsic cortical neurotransmitter systems (e.g., somatostatin), but inconsistent loss of transmitters in systems projecting to the cortex (e.g., cholinergic neurons of the basal nucleus). Biochemical and immunocytochemical studies have demonstrated that abnormal tau proteins are the major structural components of Pick bodies. A specific tau protein immunoblotting pattern different from that seen in Alzheimer's disease and certain other disorders has been suggested in some studies. A specific molecular marker and a genetic locus for familial cases are not known.

Tau-positive glial inclusions in progressive supranuclear palsy, corticobasal degeneration and Pick's disease

The presence of tau-positive glial inclusions has been recently found a consistent feature in the brains of patients with progressive supranuclear palsy (PSP), corticobasal degeneration (CBD) and Pick's disease (PiD). These inclusions are classified based on cellular origin as tau-positive astrocytes, presumably either fibrillary or protoplasmic, coiled bodies and glial threads. Immunohistochemically, their major structural component is abnormal tau proteins, similar to those found in Alzheimer's disease. Nevertheless, their morphology, including ultrastructural profile, has been suggested to be distinctive for each disease. The profile and extent of particular glial inclusions correlate well with disease phenotype. Highly characteristic correlations include tufts of abnormal fibers in PSP, astrocytic plaques and dense glial threads in CBD and ramified astrocytes and small Pick body-like inclusions in PiD. The significance of the inclusions in disease pathogenesis and their biochemical characteristics remain to be clarified. Nevertheless, these distinctive glial lesions most likely reflect fundamental alterations in isoform composition of tau as well as its specific cellular and regional expression in sporadic tauopathies.

Increased midkine levels in sera from patients with Alzheimer's disease

Midkine (MK) is a heparin binding growth factor and promotes growth, survival and migration of various cells including neurons. It is also known to accumulate in senile plaques of patients with Alzheimer's disease (AD). To investigate the involvement of serum MK in the pathophysiology of AD, serum MK levels were determined in patients with AD (n=36) and age- and sex-matched healthy controls (n=32), using an enzyme-linked immunosorbent assay (ELISA). The serum MK values of the patients with AD (median 560 and interquartile range (500-755) pg/ml) were significantly (U=278.5, P=0.0003, Mann-Whitney U-test) higher than those of the controls (median 500 and interquartile range (385-520) pg/ml). Moreover, 17 patients (47.2%) had abnormally high values of more than 600 pg/ml, but no controls (0%) did. There was no correlation between serum MK level and the mini mental state examination (MMSE) score in the patients. The demonstration of elevated MK levels in sera of patients with AD may contribute toward an understanding the pathophysiology of this disease, and provide a novel potential therapeutic strategy for decreasing neuronal damages in patients with AD. We found that serum MK levels in patients with AD were increased in comparison with those of normal controls.

Sporadic Pick's disease: a tauopathy characterized by a spectrum of pathological tau isoforms in gray and white matter

Pick's disease is characterized neuropathologically by distinct tau-immunoreactive intraneuronal inclusions known as Pick bodies and by insoluble tau proteins with predominantly three microtubule-binding repeat tau isoforms. However, recent immunohistochemical studies showed that the antibody specific for exon 10, which encodes the fourth microtubule-binding repeat, detected other tau lesions in Pick's disease. To better define the spectrum of tau pathology in Pick's disease, we used biochemical, immunohistochemical, and ultrastructural techniques to analyze the tau isoform composition in 14 Pick's disease brains. Western blot analysis showed that both three and four microtubule-binding repeat pathological tau isoforms are present in gray and white matter of various brain regions. Using phosphorylation-dependent anti-tau antibodies, we show that major tau phosphoepitopes are present in sarcosyl-insoluble gray and white matter regions of Pick's disease brains. Also, for the first time to our knowledge, we demonstrated that isoforms with four microtubule-binding repeat tau isoforms are present in Pick bodies from selected brains. Isolated tau filaments were straight or twisted and formed by three microtubule-binding repeat or four microtubule-binding repeat tau isoforms. Major tau phosphorylation-dependent and exon 10-specific epitopes were present in filaments. Therefore, Pick's disease is characterized by an accumulations of Pick bodies in the hippocampal region and cortex as well as the presence of three and four microtubule-binding repeat tau pathology in both cortical gray and white matter that distinguish this tauopathy from other neurodegenerative disorders.

Tau gene mutation K257T causes a tauopathy similar to Pick's disease

Exonic and intronic mutations in Tau cause neurodegenerative syndromes characterized by frontotemporal dementia and filamentous tau protein deposits. Here we describe a K257T missense mutation in exon 9 of Tau. The proband, a 47-yr-old male, presented with severe personality changes followed by semantic memory loss. A diagnosis of Pick's disease was made. The symptoms progressed until death at age 51. The proband's brain showed a marked frontotemporal atrophy that was most pronounced in the temporal lobes. Numerous tau-immunoreactive Pick bodies were present in the neocortex and the hippocampal formation, as well as in some subcortical brain regions. Their appearance and staining characteristics were indistinguishable from those of sporadic Pick's disease. Diffuse staining for hyperphosphorylated tau was also observed in some nerve cell bodies. Immunoblot analysis of sarkosyl-insoluble tau showed 2 major bands of 60 and 64 kDa and 2 very minor bands of 68 and 72 kDa. Upon dephosphorylation, these bands resolved into 6 bands consisting of 3-repeat and 4-repeat tau isoforms, with an overall preponderance of 3-repeat tau. Isolated tau filaments were narrow, irregularly twisted ribbons. Biochemically, recombinant tau proteins with the K257T mutation showed a reduced ability to promote microtubule assembly, suggesting that this may be the primary effect of the mutation. In addition, the K257T mutation was found to stimulate heparin-induced assembly of 3-repeat tau into filaments. Taken together, the present findings indicate that the K257T mutation in Tau can cause a dementing condition similar to Pick's disease.

Cerebellar involvement in Pick's disease: affliction of mossy fibers, monodendritic brush cells, and dentate projection neurons

Pick's disease chiefly is characterized by progressive degeneration of specific telencephalic cortical areas and associated subcortical nuclei. Components of the cerebellum also are affected. Immunoreactions for abnormally hyperphosphorylated tau protein, indicating the development of cytoskeletal anomalies in a few susceptible neuroectodermal cell types, permit visualization and identification of the pathology. Initially, accumulations of nonargyrophilic material appear in the perikarya and cellular processes of susceptible nerve cells. In some neuronal types, the abnormal deposits are transformed into more condensed inclusions, so-called Pick bodies in perikarya and Pick neurites in cellular processes, some of which become argyrophilic in the course of the disease. This study employs silver techniques and immunoreactions to draw attention to Pick's disease-associated lesions in the cerebellar cortex and cerebellar nuclei. Immunoreactive rosettes, which correspond to the terminal synaptic boutons of mossy fibers, frequently are encountered in the cerebellar granule cell layer. Some cases of Pick's disease also exhibit afflicted monodendritic brush cells in this layer. Single immunopositive Purkinje cells occasionally are seen as well. The brunt of the alterations is borne by cerebellar subdivisions receiving dense input from the telencephalic cortex through the pontocerebellar pathway (neocerebellum). The dentate nucleus shows immunoreactive axons with numerous varicose thickenings which remain confined to the reaches of this band-like nuclear gray and probably represent collaterals of altered mossy fibers. A large number of the dentate projection cells also contain the abnormal material in the perikarya, as well as in all of the neuronal processes. Many of these cells develop spherical nonargyrophilic condensations of this material. Output of the neocerebellum is conveyed to extended territories of the telencephalic cortex via the dentate nucleus and thalamus. Therefore, all of the cerebellar territories which receive major input from and generate output chiefly to the telencephalic cortex (pontocerebellum or neocerebellum) are notably afflicted in Pick's disease. Other subdivisions with preponderant input from the spinal cord and/or other noncortical sources remain intact or else are only minimally involved. It is concluded that the pattern of cerebellar involvement reflects Pick's disease-associated neocortical destruction.

Involvement of precerebellar nuclei in Pick's disease

Pick's disease is a progressive degenerative disorder of the human brain which involves not only numerous areas of the cerebral cortex but also a characteristic set of subcortical nuclei. The disorder is associated with the formation of abnormal and hyperphosphorylated tau protein, which occurs in only a few susceptible neuronal types and leads to major cytoskeletal alterations. Preferentially affected by the destructive process are small nerve cells of both cortical areas and subcortical nuclei. Immunoreactions for abnormally phosphorylated tau protein permit identification of the alterations in their entirety. In an initial step in their development, patches of a nonargyrophilic material appear, irregularly filling both the somata and neurites of afflicted cells. The abnormal material is then partially converted into condensed spindle-shaped or spherical structures, which gradually become significantly argyrophilic. Globose argyrophilic Pick bodies eventually appear within the somata, and small Pick neurites of variable sizes and shapes develop in varicose expansions of the dendritic processes. Silver staining reveals only a fraction of the abnormal material and is adequate only for diagnostic purposes, while immunostaining of the abnormal tau protein discloses the complete neuropathological picture. The present study points to a conspicuous affliction of specific precerebellar nuclei in Pick's disease. Immunoreactive punctae, probably corresponding to terminal synaptic boutons of afferent fibers, appear at sites in the inferior olive receiving intense input from the cerebral cortex. The brunt of the changes, however, are borne by the pontine gray, the arcuate nucleus, the pontobulbar body, and the paramedian reticular nucleus. Altered areas show immunoreactive punctae and an abundance of small immunoreactive nerve cells partially containing Pick bodies and Pick neurites. Again, a feature common to all the affected nuclei is that they receive major input from the cerebral cortex, while other precerebellar nuclei with preponderant input from the spinal cord and/or other noncortical sources remain unscathed or exhibit only sparse involvement. The lesional pattern which develops in specific precerebellar nuclei is interpreted to be a partial reflection of the cortical involvement of Pick's disease.

Pick's disease: cytoskeletal changes in the hypothalamic lateral tuberal nucleus

Basolateral portions of the human hypothalamus contain an extended nuclear gray, the lateral tuberal nucleus (LTN), which undergoes conspicuous pathological changes in a number of neurodegenerative diseases. The present study points to the severe affliction of this nucleus in Pick's disease (PID). Immunoreactions for abnormally phosphorylated tau-protein permit identification of the permutations. Only a fraction of the abnormal fibrillary material developing in the course of the disease shows a pronounced argyrophilia. Key features are the Pick bodies (PBs) which contain an argyrophilic material. Unusual non-spherical PBs develop in the LTN as flat structures with peripheral indentations. Small teardrop-like Pick neurites (PNs) emerge in varicose widenings of neuronal processes and display a much weaker argyrophilia. The characteristic alterations seen in PID reliably can be differentiated from lesions of the LTN which slowly emerge in the course of Alzheimer's disease (AD).

Huntingtin protein colocalizes with lesions of neurodegenerative diseases: An investigation in Huntington's, Alzheimer's, and Pick's diseases

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease associated with a CAG trinucleotide repeat expansion in a large gene on chromosome 4. The gene encodes the protein huntingtin with a polyglutamine tract encoded by the CAG repeat at the N-terminus. The number of CAG repeats in HD are significantly increased (36 to 120+) compared with the normal population (8-39). The pathological mechanism associated with the expanded CAG repeat in HD is not clear but there is evidence that polyglutamine is directly neurotoxic. We have immunolocalized huntingtin with an in-house, well-characterised, polyclonal antibody in HD, Alzheimer's disease (AD), and Picks disease (PiD) brains. Control brain tissue sections were from head injured and cerebral ischaemia cases. In HD, huntingtin was immunopositive in the surviving but damaged neurons and reactive astrocytes of the caudate and putamen. However, in AD and PiD the immunostaining was largely restricted to the characteristic intracellular inclusion bodies associated with the disease process in each case. In AD, huntingtin was localized only in the intracellular neurofibrillary tangles and dystrophic neurites within the neuritic amyloid plaques but not with the amyloid. In PiD, strongly positive huntingtin immunostaining was present within cytoplasmic Pick bodies. Our findings suggest huntingtin selectively accumulates in association with abnormal intracytoplasmic and cytoskeletal filaments of neurons and glia in neurodegenerative diseases such as HD, AD, and PiD. Cells in the CNS appear sensitive to damage by the aggregated, toxic levels of huntingtin and evidence of its interaction with neurofilaments could provide information about its potential role in the aetiology of HD.

Huntington disease: advances in molecular and cell biology

Huntington disease is an inherited neurodegeneration, for which the associated mutation was isolated in 1993. The mutation is an expansion of a CAG trinucleotide repeat, which translates to give a polyglutamine tract at the N-terminus of a large protein, huntingtin. Neither the normal nor the pathogenic functions of this protein have been identified, but it is clear that pathogenesis is mediated through the expanded polyglutamine tract within the protein, and that polyglutamine is toxic to cells. A number of proteins which interact with the N-terminal region of huntingtin have been isolated, but this has not, so far, yielded a rationale for pathogenesis. Huntingtin is found in areas of the brain that degenerate in this disease but is also associated with pathogenic inclusions in Alzheimer disease and Pick disease. It is possible that Huntington disease has pathogenic mechanisms in common with these other neurodegenerative diseases, and that the mechanism may relate to the formation of abnormal, cytoskeletal-associated, inclusions within cells.

Identification of advanced glycation end products of the Maillard reaction in Pick's disease

The recent identification of advanced glycation end products (AGEs) of the Maillard reaction in the central nervous system suggests their potential involvement in the aging process. Other studies have also suggested a possible link between AGEs and Alzheimer's disease. To investigate the role of AGEs in Pick's disease, another neurodegenerative disease associated with dementia, we examined the AGE-immunoreaction in Pick's bodies and ballooned neurons, two characteristic neuropathological features of Pick's disease, using antibodies against identified AGE-structures, N epsilon-(carboxymethyl)lysine and pentosidine. These two structures were observed immunohistochemically in Pick's bodies and ballooned neurons of brain tissues obtained at autopsy from three elderly patients diagnosed with Pick's disease. These immunoreactions were further confirmed by absorption experiments and double-immunostaining. The present findings suggest that AGEs are involved in the pathology of Pick's disease.

Complement activation on human neuroblastoma cell lines in vitro: route of activation and expression of functional complement regulatory proteins

Two human neuroblastoma cell lines activated the classical pathway of complement in serum. Activation caused the opsonisation of these cells with complement fragments but with moderate cell killing. Neuroblastoma expressed regulators MCP and CD59 but did not express DAF or CR1. Neutralisation of CD59 rendered the cells susceptible to killing. Neuroblastoma also expressed C1-inhibitor, factor H, clusterin and S-protein. Expression of several regulators was enhanced by incubation with cytokines. Complement inhibition using soluble CRI markedly reduced opsonisation and killing of neuroblastoma. Our results suggest that complement might play a role in neuronal loss and that treatment with complement inhibitors might be of therapeutic value.